The present invention relates to a motor and a recording and/or reproducing apparatus using the motor, and particularly to a motor and a recording and/or reproducing apparatus using the motor, which is characterized by the bearing construction.
FIG. 6 shows a spindle motor constituted by a conventional bearing construction.
In FIG. 6, reference numeral 20 designates a base (chassis), on which is caulked and mounted an oil-contained bearing 21. A center shaft 23 is pressed into and secured to a hub bed 22 as a rotary body, the center shaft 23 being inserted into the oil-contained bearing 21.
Thrust bearings 24 are mounted through balls 25 in kerves 26, 26 provided in the hub bed 22 and at positions opposite to the kerves 26, the hub bed 22 being rotatable about the center shaft 23. Reference numeral 27 designates a retainer, which performs a function to control a movement of the ball 25 in a lateral direction of a paper surface. There is generated a force for rotating the hub bed 22 by means of the action of a magnet 29 fixedly mounted on a rotor yoke 28 mounted on the hub bed 22 and a current flowing through a coil mounted on the base 20.
However, the aforementioned prior art had the following problems.
A clearance is produced between the oil-contained bearing 21 and the center shaft 23, thus causing a deflection in the center shaft 23 during rotation.
Further, a step for pressing the center shaft 23 into the hub bed 22 and a step of fastening the oil-contained bearing 21 to the base are required. Furthermore, the cost of the center shaft 23 is high. Further, a slip friction occurs in the oil-contained bearing 21.
Moreover, with recent trend of a smaller, thinner computer and higher performance of a computer, a floppy disk drive (FDD) as a memory has been demanded to be thinner. Particularly, in a 3.5 inch FDD, a thickness of 42 mm at the outset of development has been changed to 25.4 mm, and further, a 1/2 inch (12.7 mm) height thereof has been marketed. Now, there is a demand for to a thickness of 10 mm or so.
On the other hand, format of a 3.5 inch disk remains unchanged. Further, the provision of front-loading is necessary for the sake of using convenience. In this case, an absolute condition is to make a spindle motor thinner for making a drive thinner. A precondition for making a thinner spindle motor is to provide a thinner bearing, which is recongnized as a difficult problem.
In addition, with the trend of portability of computers represented by a personal computer, a word processor and the like, a lower power consumption FDD has been strongly demanded in terms of the necessity for relieving power consumption of a battery.
Further, since a current market price of FDD is 1/10 or less than the original market price, the spindle motor naturally becomes the target of being lowered in cost.